[patch] staging: lowmemorykiller: remove bogus NULL check

[patch] staging: lowmemorykiller: remove bogus NULL check

[Dan Carpenter]

The NULL checking here doesn't make sense, so it causes a static checker
warning.  It turns out that p->mm can't be NULL so the inconsistency is
harmless and we should just remove the check.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c
index c79f224..24d2745 100644
--- a/drivers/staging/android/lowmemorykiller.c
+++ b/drivers/staging/android/lowmemorykiller.c
@@ -131,7 +131,7 @@ static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc)
 		if (!p)
 			continue;
 
-		if (task_lmk_waiting(p) && p->mm &&
+		if (task_lmk_waiting(p) &&
 		    time_before_eq(jiffies, lowmem_deathpending_timeout)) {
 			task_unlock(p);
 			rcu_read_unlock();

Re: [patch] staging: lowmemorykiller: remove bogus NULL check

[Tetsuo Handa]

Dan Carpenter wrote:
> The NULL checking here doesn't make sense, so it causes a static checker
> warning.  It turns out that p->mm can't be NULL so the inconsistency is
> harmless and we should just remove the check.

Commit 77ed2c5745d9 ("android,lowmemorykiller: Don't abuse TIF_MEMDIE.")
replaced test_tsk_thread_flag(p, TIF_MEMDIE) with task_lmk_waiting(p) && p->mm
because TIF_MEMDIE is cleared after p->mm became NULL whereas
PFA_LMK_WAITING is not cleared after p->mm became NULL.
But p is a thread which is guaranteed to be p->mm != NULL.

> 
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

> 
> diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c
> index c79f224..24d2745 100644
> --- a/drivers/staging/android/lowmemorykiller.c
> +++ b/drivers/staging/android/lowmemorykiller.c
> @@ -131,7 +131,7 @@ static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc)
>  		if (!p)
>  			continue;
>  
> -		if (task_lmk_waiting(p) && p->mm &&
> +		if (task_lmk_waiting(p) &&
>  		    time_before_eq(jiffies, lowmem_deathpending_timeout)) {
>  			task_unlock(p);
>  			rcu_read_unlock();
>